Liquid level indicator



Aug, 13, 1935. E. A. ROCKWELL LIQUID LEVEL INDICATOR Filed June 8, 19312 Sheets-Sheet l //v VEN TOR EDWAE'D ,4 Pam WELL. B y

A TTORNE Aug. 13, 1935.

E. A. ROCKWELL LIQUID LEVEL INDICATOR ATTORNEY Patented Aug. 13, I935Edward 'sgaackweu; Chicago, "Iii, assi'gnti to PatentflEngineeringCorporation, New York,

N Y acorporation of Delaware ApplieationJune 811931, Serial.No.542,884 3Q N 1,1 M

"This" invention relates toimprovements in liq-J uid level indicators ofthe 'hydrostatic typefor indicating the quantity of liquid ina containeror tank, and-more particularly-to such indicators-w 5; where theindicating instrument or gagevis ilo-u cated at adistance from the tank.

The present invention "relates more specificallyt to indicators of thesuction hydrostativstype. wherein the gage orindicatingmember isiactu-tated by vacuum; Such indicators maybe divided) into two general typesThe first type employs the" vacu-um. gage inconnected directly tothesuctiontube or pipe for withdrawing the liquid from the container;and

in, this connection is made at a point above the surface of the liquidwhose depth is to be meas-t ured. This point of connection is the datumline, and'the gage only reads correctly when there is no flow in thesuction tube for therreason that during the flow the gagewillindicaterthe total vacuum necessary to cause the flow of liquid inaddition to that necessary to lifttheliquid to the datum line. Suchindicators are not suitable wherethere is a constantly'changing rate offlow;

of the liquid, and are subject tovariationbecause of temperature changesand because of any state of change in the character of the liquid while;flowing or standing in thefsuction pipe. Such in-;

dicators must have a valve in the suction pipe to r 3 hold the level ofliquid tobemeasured, when no liquid is being withdrawn from the tank.

t The second type of indicator is that in which dition existing abovethe column in the sp ace between it and the gage, "Ihis arrangementwill:

give correct readings regardless of the fiow'of liquid through thesuction pipe, ;and if a com striction or valve is placed in theaforesaid connection between the liquid column and the s uction pipe;this type of indicator can be made'to register approximately only thevacuum neces-' sary to balance that portion of the liquid-column betweenthe datum line and the surfacegof the liquid to be measured whichdepends upon-the amount of liquid in the containern This second type,when there is no flow, cmust also depend upon a shut-ofi or check valveinthe suction pipe in order to maintain the eading cm the gage. Valvesfor this purpose are undesirable desirable to mount; the gageproperiupon the inner forfreeing the same from obstructionawith:

7 lai sin- 42i for several reasonsg inthe event they leak, the gage willread incorrectly and'will usually read full insteadof iemptyft Thepresence of such valves preventsrthe blowing out of the suction pipeoften necessary in servicing. t .1 i Qbviousl'y, bothof these types failif all the liquid is drawn out of the tank, as in this event theliquid-in the suction pipe. in the firsttype or theliquid colunm in thesecond type is no longer sealed and falls .backinto the container. Thisbreaksjthe vacuum on the gage, causing it to read fulliwith anemptytanks: a

.An object of thetinvention is toprovide a liquid level indicator thatwill be free'from the aforesaid objections and from inaccuracies causedby cator and its associated parts and piping,'and .a

device fthat will be free. from other objectionsheretoforemetwithinindicators of the hydro.- 7 static; type, all as more; fully"hereinafter re 20 ferred to. t

I Anotherobject is to provide an indicator that issimple-and cheaptoconstruct and which may be" easily. installed: on jautomobiles where itis Strument board in;front of thedriver, theother 25 parts beingassembled iasa tank unit andmplaced in the fuel; tank at a distance fromthe gage.:

Another object is toprovide alevelindicator wherein float valves areeliminated, andwhich is adapted ior use in connection with afuel pump orzsuctiontdevice. r 7 "Another object is? to provide an indicatorv thatmay be-used with tanks and-pipingwhere it is possible to; blow out thepiping in the usual manout injurytoatheigageyu a ,t t

A further .object isgto provide an indicator" wherein the parts;associated" with the tank or container holdingthe liquid whoseleveltherein 0 t is to be indicatedon the gage, are-compactlytassembled'intot'a tank tunit adapted to beeasily ata tached to thenwallof the tank so as to project only slightly Ltherefrom, particularly ifplaced on the "top ofvthe tank. This is ofaimp'ortance 45 l-9which nuswith l-iquid andiiormsa liquid sealously, many modifications may be madein the construction and assembly herein described, without however,departing from the appended claims.

In the accompanying drawings:-

Figure 1 is a diagrammatic illustration, partly in elevation and partlyin section, of the complete liquid level indicator as applied to anautomobile showing the complete assembly and operating connections tothe fuel pump;"

Figure 2 is a view, partly in section, of the compensator or tank unitof the indicator;

Figure 3 is a view on the line ab through the casing Figure 2, with thepipes broken away to show the relative arrangement of same;

Figure 4 is a plan view, looking down on the top of the unit Figure 2;

Figure 5 is a sectional view of the valve shown in Figure 2;

Figure 6 is a view, partly in section, of a modification of the tankunit Figure 2;

Figure '7 is a view, partly in section, of another modification of thetank unit Figure 2;

Figure 8 is another view of the unit shown in Figure '7; and 1 Figure 9is an enlarged sectional view of the valve 42 in Figure '6.

In Figure 1, the numeral l denotes the fuel tank. of an automobilehaving therein the compensator or tank-end of the indicator hereinaftertermed .the tank unit, as shown in Figure 2.

The tank unit comprises a flanged casing l constructed in any suitablemanner and having therein a chamber l2, lying partly within the tankill, the casing being-secured to the apertured wall 13 ofv the tank byanymeans such as the. bolts or screws 14. This enables the device to beused on tanks without sacrificing head room, and provides that theliquid level in the chamber [2 shall be practicallyon a line with theupper wall I3 of the tank.

" andbeing positioned in a sump H in the tank [0. The end l6 shouldbe'aboveth'e loop 26 forming a liquid trap in the compensating tube tobe presently described, to prevent ingress of air to chamber 12 when thetank is empty. The pipe l extends outwardly from the tank unit and maybe of sufficient length to connect to the usual fuel pump assembly shownin Figure'l which may be of any suitable type. A check valve I8 isusually found in such pumps and opens toward the pump, preventing thereturn of liquid through the suction pipe I5 although this return wouldnot affect the operationefthe gage. f

Secured to the bottomor pipe 5 and preferably supported thereby is thecup 'orcatch basiii for the bottom end of pipe tube or-member 2-! whichextends upwardly, the end 22 thereof opening into chamber ILQSurrQundingthe end 20 of this pipeis'the' screen-23 secured to the pipe andtheuppered'ge' of cup letoprevent dirt and water from-entering the" pipe.and-thereby getting into chamber l2. This .screen isso shaped andpositioned in tank l0 asto be washed by the movement of the liquid inthetank so that pipe 2| and soldered theretofi'or to the screen.

The cup l9 always forms a liquid trap about the lower end of the tube ormember 21, the liquid in which will constitute a liquid column, even ifthe level of liquid in the tank should fall below the bottom of 19 andeven if all of the liquid is drained from the tank, provided the vacuumin chamber l2 above the liquid column is sufficient to support it.

The small pipe 25 being bent to form the loop 26 forming a liquid trap,the end 21 is thrust inside of pipe I5 until it strikes the bend 28therein. The exact position of end 27 is not important 7 provided it issubject to the suction in pipe [5,

but Figure 2 shows the average relative position of this end 21in'relation to the end 29 of pipe 30 which together with 25, forms aconnection between the suction pipe l5 and the chamber l2.

The end 29 of the pipe 38 projects upwardly in chamber I2 a definitedistance in order to definitely determine the liquid level therein;liquid in this chamber will rise to the upper edge of the end 29 andoverflow, the liquid level being maintained at this point as hereinafterdescribed, and forming the datum hne for the indicator. v

The pipe 351 extends downwardly as shown, having the loop 24 forming aliquid trap therein, and then extends upwardly and connects to theback-pressure valve 3|. The pipe 25, having the trap 25,, extendsupwardly outside pipe l5, and has bend 32 therein and then extendsdownwardly andconnects to the top of valve 3!.

Valve 3!. performs no function in connection;

with the indicator per se except to prevent backpressure, and is placedas shown merely to permit blowing out the fuel supply pipe !5, as here,-inafter referred to. This valve may be of any suitable construction butas shown in Figure 5 has a restriction orifice 32a in its body openingagainst the movable disc 33, which opens up wardly, Figure 5, and isheld normally against its seat by gravity and the weight 36.

The restriction orifice 32 must be much smaller than the bore of pipe 2|and may be placed anywhere in the connection formed by pipes 25 and 30between pipe l5 and chamber l2 when valve 3| is not used. When valve 3|is used, it merely forms a convenient means of inserting thisrestrictionin the connection aforesaid which comprises the pipe 25, trap26, trap 25 and pipe 39. Trap 2 3 is not absolutely essential and couldbe omitted. This connection between the suction means l5 and the liquidcolumn in El is hereinafter termed a compensating tube. The restrictionorifice 32a is employed to prevent the toorapid withdrawal of fluid andvapor from the chamber 12, and eliminates the necessity ofaccurately'determ'ining the relative sizing of the pipes 3B, 2! and 21.

In the event the piping on the automobile isblown out, as often done tofree the same from dirt and water, the air will enter the tank via.

pipe l5, but by reason of the liquid trap about the end 20 of pipe 2icannot find its way through said pipe into chamber l2 and then via pipe35 to the gage. If air enters pipe 25 of the compensating tube at theend 27,- it will pass down-- wards therein to the chamber 3'! in thevalve 3! but can go no further because the disc 33 is on its seat.Therefore, when blowing out the system,

no air can reach the chamber i2 and pass to the gage 36 which is inconsequence protected from damage. The tank H! of course is vented tothe atmosphere through the usual hole in he filler cap 38.

necessity of having the gage 36 assembled and connected. The. pipes Iand35 are conveniently clamped, between the two sides of the casing I;

cating means 36.

. It will be observed that the deviceshown in Figure 2 forms acompletetank unit and may be placed on the tank assembly as such,;without the asshown in the drawings. Theunit is connected 7 by couplings.40,4| to itsassociated pipes.

1. reason- I i r i A' further modification embodying both the- ..ascreen 5|.

\ The modification ofthe tankunit shown. in.

spring against aseat 51 communicating with,

the intake orifice in the'head of the valve body. .The restrictionorifice necessary in' this formof compensating means is the hole 45, and

thea area of the valve seat should-be. of much greater crosssectionthan.that of the orifice' This. valve performs a double functionaspresently' described. 1

The bottom 46 of pipe 15. is cut off as shown,

Figure 6, so that theend thereof is above the screen 23. i i l .=If thepiping system is blown out," air entering,

via;:pipe I5 cannot reach the chamber |2, pipe 35 and gage 35, as thevalve 42 onlyopens inward-. ly. and pressurein pipe |5 only servestoclose it more tightly. As the bottom of pipe 2| is sealed:

byreason of liquid in the 'cup |9 no air can en- 1 ter 2|. v a

...If.valve 42 should failand permit the operating condition in. chamber|2 to change, the gage will not read correctly. The liquid sealarrangement shown in Figure 2 is preferable for this valve and a liquidseal is shownin Figures 7 and and then extending downwardly, terminatingat 49 slightly above the bottom of bend -4|.- The pipe 2| extends fromthe chamber |2 to a point= slightly below the bend 41 and is provided'wi th The valve 42 is placed in the top of bend 48. i

f; In operation, the tank unit being connected to the gage 36 and to afuelpump 52 of any suitable type commonly used to supply gasoline viapipe 1 53 to the usual carburetor 54, the tank I 0 is filled withgasoline. If the fuel pump is not operating the gasoline willflowupwardly in pipes l5 and 2| and some air will therefore be trapped inthe chamber l2. The gage 36 connected to this .chamberwill now registerfull andsome of the indicating liquid thereinwill be forced up into theoverflow space 56. i

Whenthe pump starts itdraws gasoline up the pipe |5 which creates asuction on the end 21 of the tube25,'which being connectedto the tube 30(via valve 3|), the latter having its datum line of the device isestablished and this levelremains practically constant, a small,quantity of;,gasolinebeing sucked through the com-.

pensating tube intol5.

This withdrawal of gasoline together with air or. vapor 'thatjmay be inthe chamber l2 by the compensating means automatically and continuously.compensates .or, corrects for temperature changes, for-,anyvapors thatmay be present 3 and for any differences that-may occur in the gasolinelevel in chamber I2 while the, fuel pump:

is not inq,use. 'I'hevalve 3| playsnopart in the operation of:-.thede.vice except the restriction 32 therein prevents too rapidsuction. on the.

chamber l2;

In the event the pipeline terminating in .15v

is blown'out, the-valve 3| closes and prevents air fromenteringthechamber I2. This valve is preferably immersed in the gasoline in ID i asshown, towetthevalve'member 33 (preferably of treated fabric) whichoperates best when immersed inliquid. .1 z r The -modification shown inFigure 6 operates asjust described except that instead of the COm-.pensating tube shown in Figure 2, the valve 42 is used. When suctionoccurs inthe pipe l5, the valve 42 opens and permits the contents ofcham ber. |2,to, be withdrawn, including liquid, down to a datum linedepending, upon the locationbf theentrancehole 45 in the valve. Iftheyalve 42 should leak, the device will not be prdperlypermit=communication betweenthe chamber l2. and a space within pipe .15extending between. the bend 48 and bend 4'|,.as the'latter forms a.

liquid trap. This is because the end 49 of IS is-trapped injtheliquid inthe sump I! and the outgoing end of l5, that is, the end connectedto thepump, is trapped by the liquid in the bend 41." 1 it In bothof themodifications Figures 6 and 7,

the-valve 42 .acts touprevent air entering cham-" ber |2- in. case thepipingis'blown out as previously mentionedp. i

.Usuallyby the time the tank is filled, the liquid 55 in the gageassumes a position on the scalewhich indicates the quantity of .liquid'in tank |0...-.This scale is usually graduated to read from -ful1.to'fempty as shown in Figure 1. The tube 58 may extend upwards asindicatedat 56 .to provide room for the liquid displaced by pressure during theinitial filling of the tank where there is no liquid in cup I9. Usuallyi9 is sealed and the liquid 55 is not forced into the. overflow space 56by pressure, as just de-' scribed.

It will be observed that the vacuum in chamber l2 registered by thegageywill always be proportional to the hydrostatic head of gasolinefrom the surface of the liquid'in the tank, to

the datum. line. If 60, Figure 6, is the datum line and 6| the liquidlevelthe vacuum willalways be equal to the. column of liquid in the Thegage isgradu-- tube ZS) connected to any sourceo'fi suction such as theintake manifold of an. engine. As the compensating tube or pipe is quitesmall the very small amount of gasoline sucked through the pipe could bedisregarded. When this is done, themain supply of gasoline may be takenout of pipeliwhich would then have no part in the operation of theindicator- I The different forms of theinvention herein described allhavethe pipe 21 forming. a liquid column, as well as a compensatingmeans-the compensating tube of Figure 2 or the valve 42 of Figure 6 or'7. In all three forms the compensating means includes a restrictionsuch as the .orifice 32.

.In some'forms of the invention thecha'mber' l2 may be part of theliquid column and could be a section of pipe 2!. Pipe may also be partof the column. The reason the liquid column is preferably provided withchamber I2 as shown is to provide a convenient place to trap fluid toform the datum line aswell as provide an expansion space of considerablecontent in proportion to the smallcontent of the pipe 35 so that anyexpansionof air or gas in the free space in 35' due to temperaturechanges will not seriously alter the liquid level forming the datumline. In this connection chamber l2 functions as a combination liquidtrap and expansion chamber.

Loop 26 should be below the opening l6 into the pipe I5, that is to say,below the upper edge of the said opening.

The position of loop 24 is immaterial; the only reason it is broughtdown and into proxim- .to, suction means separate from said first meansfor withdrawing liquid. from said container, a suction operated valveoperatively connected between said column and said suction means topermit back pressure toflow through said suction means to saidcontainer, and indicating means communicating with said column.

2. In combination with a tank, a unit struc ture-adapted to be mountedin said tank'co'mprising a casing forming a chamber, a suction pipesecured to said casing and extending downwardly therefrom and adapted towithdraw liquid from said tank, a gage pipe secured to said casing andcommunicating with the upper portion of said chamber, a member adaptedto form a liquid column secured to saidcasing and extending downwardlytherefrom and having its upper end in communication with the lowerportion of said chamber, a tube connecting said suction pipe and saidchamber, and a valve'in'said tube positioned below the bottom of saidchain bet and adapted to beimmersed in liquid when saidunit structure ismounted in a tank.

3. -A unit structure adapted. to be mounted in genres a tank comprisinga casing formingla chamber, asuetion pipe passing through the walls ofsaid casing and. through said chamber and extending downwardly therefromand then. upwardly to form a liquid trap portion below said chamber,said pipe having. a bend abovesaid trap portion, said pipe continuingdownwardly from saidbend and having its tank end terminating abovesaidtrap portion, .a tubular member connected with said chamber andextending downwardly therefrom. and terminating near the tank end'otsaid suction pipe, and a valve permittingcommunication between said.chamber and that portion or" said pipe lying between theliquid trapportion and tank end thereof.

4. In a liquid level indicatonthe combination with a tank adapted tohold liquid, of a suction pipe terminating in said tank, said pipehaving two U bends therein within said tank, one above the other, thelower bend adapted to form a liquid trap in said pipe, a chamber, a gageconnected thereto, means separate from said suction pipe adapted toconduct liquid from said tank to said chamber, and means adapted tomaintain a constant liquid level in said chamber connected to saidsuction pipe.

5. In a liquid level indicator, a tank, a liquid. column connectedthereto, a suction pipe separate from said column and adapted towithdraw liquid from the tank, a passage between said column and pipe, avalve in said passage, and a constriction in said valve adapted torestrictthei fiow of fluid therethrough.

I 6. In a liquid level indicator, a container, means to form a liquidcolumn connected thereto, a chamber connected to said column, suctionmeans separate from said liquid column for withdrawing liquid from saidcontainer, a passage between said chamber and said suction means, saidpassage being continuous during all conditions of: operation of theindicator, means for maintaining a constant liquid level in saidchamber, indicating means connecting with said chamber and a valve inthe passage between the chamber and the suction means adapted to protectsaid indicating means and to permit back pressure to flow through saidsuction means to the icon-.

tainer.

7. In combination with a tank, a casing adapted to be mountedin a wallof said tank, a suction pipe passing through said easing into the tankand terminating near the bottom thereof, a chamber in said casing, atubular means adapted to form a liquid column depending from said casingand in communication with said chamber and terminating near the bottomof said tank, a compensating tube connecting with said. suction pipe atthe point where it passes through said casing and extending downwardlybelow the bottom of said tubular member and thence up-: wardlyterminating within said chamber, indicating means connected to saidchamber and. adapted to indicate fluctuations in subatmospheric pressuretherein and a valve located in the compensating tube and adapted toprotect the indicating means and permit back-pressure to flow throughfrom the suction pipe to the tank.

EDWARD A. ROCKWELL.

